1. Technical Field
This invention relates to a method and apparatus for identification of histology samples. Many samples of tissue are taken for microscopic examination in the diagnosis and monitoring of a variety of illnesses and conditions. Before a microscopic examination can take place, a tissue sample must be treated to remove water, impregnated with an embedding medium such as wax, and then finally sectioned using a microtome. Suitable sections are then mounted on slides for examination.
Hospital and commercial laboratories have highly efficient systems for performing the necessary sequence of operations. Each tissue sample is placed in a perforated cassette which is marked with an identification number either manually in pencil or by hot foil stamping.
The cassette is closed with a lid and processed through the dehydration and wax impregnation stages. The sample is then emptied from the cassette into a stainless steel mould, the cassette is mounted on top of the mould and the whole assembly is set in wax. The stainless steel mould is removed, leaving the cassette with a wax block containing the treated sample moulded to its under-side. The identification number is still visible on the cassette to identify the sample.
The wax block and sample are then sliced using a microtome to provide sections for mounting on one or more slides. The cassette and the remainder of the sample are stored for future reference.
2. Background Art
At this stage it becomes necessary to transfer the identification number to each of the slides, either manually by pencilling onto a matt area on the slide or by manually scribing the slide with a diamond scriber or by the application of a computer printed label identical with that on the cassette. Great care is taken to ensure the correct labelling of all the slides but mistakes can occur.
It has also been proposed to prepare a cassette with the identification number etched by laser and to prepare some correspondingly identified slides. This requires considerable capital investment for the laser equipment and, particularly when it is not known how many slides will be needed for each sample, any surplus slides will be wasted because the number cannot be removed. With computer generated labels, any surplus labels must also be discarded but this is less expensive.
It has recently been proposed to form elongate labelling elements of a material which can be sectioned by microtome and to embed the labelling elements with the sample in the wax embedding medium. The elements are then sectioned with the tissue sample so that each slide will carry a thin section of the labelling elements to identify it.
However, the two stage relief moulding process proposed for making the elongate labelling elements would appear to be time consuming and incompatible with high speed laboratory processing. Further, the large size of the elements which would be formed by this process would require increased consumption of processing materials such as wax for even small tissue samples and larger cassettes.